2024 Fleetwood 28A no power to micowave with house battery only

bid_time might have exaggerated a wee but, but the answer is solid. Very few RVs come with an inverter, and both AC and microwave are 120 volt AC appliances, not 12 volt DC. So nobody runs either while boondocking. If you simply MUST have a microwave to live, you will have to buy and install an inverter, and for a microwave, said inverter MUST be pure sine wave unit, not a modified sine wave one. 

The microwave is not a 12V appliance, it is 120V. You can not get 120V out of a  12V battery unless you have an inverter. The majority of RV’s do not have an inverter. Even if you did, it would only run the microwave for about 10 seconds, unless you had about  12 batteries and a 1200W inverter. Also the same with the air conditioner, except you would have to have a huge bank of batteries and a mega inverter.